Silver halide developer containing a film-forming plastic and a water insoluble finely comminuted solid substance



Nov. 4, 1952 LAND 2,616,807

- SILVER HALIDE DEVELOPER CONTAINING A FILM-FORMNG PLASTIC AND A WATER INSOLUBLE FINELY COMMINUTED SQLID SUBSTANCE Filed NOV. 29, 1946 o Base Layer W 7 Image Carrying Layer Patented Nov. 4, 1952 UNITED STATES PATENT OFFICE SILVER 'HALIDE DEVELOPER CONTAINING A FILM-FORMING PLASTIC AND A WAT-ER *INSQLUBLE FINELY COMMINU'IEED SOLID Edwin Land, Cambridge, Mass., assignor "to Polaroid Corporation, Cambridge, Mass aaicorporation .of Delaware Application November 29, 1,946,.er1ia1No.7.12,886

15 Claims. 1

.This inv ntion relates to photog phy and more p rticu arly t novel ph tograph c fil units and p oc se A principal object of the present invention is to provide a novel photographic process of the ype wh re n a visco s film-forming material is utilized in forming animage-receiving layer for the purpose of receiving a positive image of a subject image, and wherein said image-receiving 1ayer hasa greater resistance to cracking.

Another object of the present invention is to provide a process for forming an image-receiving layer of the above character having amatte surface by the use of a finely comminuted substance.

Another object of the invention is to provide ,a photographic material comprising a water solution of a developer, a film-forming material, and a water-insoluble substance capable of giving .a matte surface to a film formed by the film-forming material.

Another object of the invention is to provide ,a composite photographic film unit comprising a photosensitive layer, a container having therein a liquid composition including a film-forming material, an image-carrying layer, and a substance capable of imparting a matte surface to a film formed by said film-forming material when said liquid is spread in contact with said imagecarryi g layer.

These-and other objects of the invention will in part be obvious andwill in part appearhereinafter.

The invention accordingly comprises the product possessing the features, properties and the relation of components and the process involving.

the several steps and the relation and the order of one or more of such stepswith respect to each of the others which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated i in the claims. I

Fora fuller understanding of the nature and objects of the -invention, reference should be had to the following detailed description, talgen in connection with the accompanying drawing.

This invention relates generally tonovejljphotographic processes of the type wherein a photosensitive layer is subjected to a "predetermined processing by having spread adjacent thereto and preferably contact therewitha layer of a liquid --proce ssing agent comprising as an ingredient thereof a film-forming material, the lattier material' being adapted to provide adjacent said photosensitive layer a dimensionally stable solid film. In its preferred form the processing carried- 'layerwas subjected *inthe formation of the latent age- "In a preferred modification of the present invention,-the process comprises creating within a film .un'i't, containing said photosensitive layer, a layer of liquid composition including a solvent for a developer and a film-forming material, causing said 'film-formingma-terial to createa solid, substantially {dimensionally stable filmhaving a matte surface, developing said'laten't image in said photosensitive -materialby-means of said developer, creating positive image-forming components under the selective control of said development, transferring said positive imageforming componentsto said formed film and converting said components to a visible positive image at least partially in said formed film.

A preferred film unit for use with such a process comprises a layer of photosensitive material such as 'a noble metal halide, for example, a silver halide, another layer, and a container having therein a liquid composition and positioned for discharge of its liquid content between said "layers. The liquid composition preferably comprises an'alkalin'e aqueous solution of a developer such ashydroquinone, asilver halide solvent such as sodium thiosuliate, a preservative such as sodium sulfite, a film-forming "material such as sodium carboxymethyl cellulose, and a relatively "insoluble inert colloidal substance capable of imparting a matte surface "to a film formed by means of the --f-ilm-forming material. The other layerfinthefilmunit preferably serves as a carrier for the 'final "positive image and is hereinafter referred to as an image-carrying layer.

This preferred type of film unit is shown in the drawing wherein there is provided a base layer It adapted to carry-on one surface thereof a photosensitive layer 1 -I. There is also provided an image-carrying layer l2 which maybe suitably joined to the base layer l0. Between the imagecarrying layer I2 and the photosensitive layer l i there is positioned a container l3, adapted to have "therein the liquid composition. This container canbe attached to either thephotosensitive layer "H or the-image-carrying"layer l2. On the upper-surface of the image-carrying layer '12, there is "preferably incorporated a material such as leadacetate "which aids, among other things, the formation of a stable film.

The base layer I is preferably made of a suitable film base material such as a cellulosic ester, or mixed ester such as cellulose nitrate, cellulose acetate, celululose acetate propionate, or other substances capable of supporting a photosensitive emulsion. e

The image-carrying layer 12, in a preferred embodiment of the invention, is formed of a photographic material known in the art as baryta paper. This layer is preferably permeable to the liquid composition and may also be manufactured from other substances such as gelatin or paper. It may also be made of regenerated cellulose, polyhydroxy alkanes such as polyvinyl alcohol, sodium alginate, certain of the cellulose ethers such as methyl cellulose, and their derivatives such as sodium carboxymethyl cellulose or hydroxyethyl cellulose, carbohydrates such as gums or starch, and mixtures of these materials where the latter are compatible.

In a preferred embodiment of the invention, this film-forming material adheres strongly to the image-carrying layer and forms therewith an inseparable coating.

The film-forming material may comprise a high molecular weight polymer preferably from the class consisting of the water-soluble, alkaliinert polymers such' as hydroxyethyl cellulose, sodium carboxymethyl cellulose and polymethacrylic acid. Such other cellulosic ethers as aluminum carboxymethyl cellulose may also be satisfactorily used for this purpose. In accordance with the present invention there is included in the above-described liquid composition an inert substance, such as silica aerogel, fullers earth, diatomaceous earth, kieselguhr, and wood fiour. In general, it may be stated that these inert substances should have the ability of forming a more or less discontinuous film. The property of these substances to make the film more or less discontinuous also seems to aid in preventing the cracking of the film. This is particularly true when a thick film is created and a film-forming material is used of the type such as sodium carboxymethyl cellulose which crosslinks with metals, such as lead, to form a very brittle film.

In the use of inert substances of the above type which have high absorptive characteristics,

it has been found that when they are added to the liquid composition they should be first treated so as to remove any absorbed air, since the oxygen in the air may have a deleterious efiect blowing in nitrogen. Other methods of removing absorbed oxygen are equally valuable.

Several nonlimiting examples of preferred liquid compositions for use in the present invention are as follows: v

kieselguhr may be incorporated in liquid compositions of the type described above and they are preferably added in the ratio of about 1 part, or less, of the added material to 25 parts of the liquid composition.

When the film unit of the type described in connection with the drawing is used, the photosensitive layer II is exposed to actinic light either through the transparent base layer I0 or, if the base layer be opaque, the photosensitive layer may be exposed by moving either the photosensitive layer II or the image-carrying layer I2 and exposing the photosensitive layer directly Without any of the light passing through any of the layers of the film unit.

The composite film unit is then processed by the application of a mechanical stress to the film unit for the purpose of releasing the liquid composition from the container l3 and spreading this liquid composition in a uniform thin film between the photosensitive layer H and the image-carrying layer l2. The developer in the liquid composition develops the exposed photosensitive material and the silver halide solvent forms soluble image-forming complexes with the unexposed and undeveloped photosensitive material. Meanwhile, the film-forming material is forming a dimensionally stable image-receiving layer which preferably adheres to the imagecarrying layer. The image-forming complexes are transferred to this image-receiving layer where they are developed to a positive image by unused developer in the liquid composition.

The added inert material makes the formed film more or less discontinuous and thereby imparts to the formed film a greater resistance to cracking. Since the inert substance, such as Santocel, has a low refractive index, and imparts to the formed film a more or less rough surface, this surface has an excellent matte finish.

While the preferred liquid composition described above includes all or most of the active materials for forming the positive image, this requirement is not essential and one or more of the materials in the liquid may be included in solid form in the film unit in position to be dissolved by the liquid as it is spread through the film unit. 1

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limited sense.

What is claimed is: a

1. A photographic product for forming transfer prints comprising a rupturable container holding a liquid, and a sheet support on which said container is mounted, said sheet support providing a spreadingsurface having a 'liquidreceiving area adjacent said container onto which sa d liquid is spreadable directly from said contamer, the liquid in the container comprising a f h d d l esclv ntincluding water for said developer, a water-soluble silver halide solvent, a water-soluble film-forming plastic in solution and a water-insoluble. finely comminuted solid substance chemically inert to the contents of said liquid in suspension, said finely comminuted substance having a low refractive index, the container contents, when spread on said liquid-receiving area, being sufficient in amount and capable of forming a transfer print of a latent image contained in an area of silver halide emulsion equivalent to said liquid-receiving area, said finely comminuted substance imparting to the solid plastic film that is obtained upon the drying of the liquid a matte surface and a greater resistance to cracking.

2. The product of claim 1 wherein the finely comminuted substance is silica aerogel.

3. The product of claim 1 wherein the finely comminuted substance is diatomaceous earth.

4. The product of claim 1 wherein the finely comminuted substance is wood flour.

5. A photographic processing composition for forming'transfer prints of latent images contained in silver halide emulsions, which composition comprises a silver'halide developer, a solvent including water for said developer, an alkali, a water-soluble silver halide solvent, a watersoluble film-forming plastic, said plastic forming a 'solid film upon removal of the liquid content of said composition, and a water-insoluble'finely comminuted solid substance chemically inert to the developer, alkali, silver halide solvent and plastic, said composition, when spread in a thin layer between a photosensitive silver halide emulsion containing a latent image and a printreceiving layer, being capable of forming a transfer print of said latent image and of forming a solid film of said plastic throughout the spread area when the liquid content of the composition has been absorbed and evaporated therefrom, said finely comminuted substance imparting a matte surface to said film and increasing the resistance thereof to cracking.

6. The composition of claim 5 wherein the finely comminuted substance is silica aerogel.

7. The composition of claim 5 wherein the finely comminuted substance is diatomaceous earth.

8. The composition of claim 5 wherein the finely comminuted substance is wood fiour.

9. In a method of forming transfer prints of a latent image contained in a predetermined area of a silver halide layer of a photosensitive sheet material wherein a viscous liquid processing agent, containing all of the liquid for effecting the formation of the transfer Print and also containing a solid film-forming colloid, is spread in a layer between said photosensitive sheet material and another sheet material, the liquid from said processing agent being absorbed by said photosensitive sheet material and during absorption distributing to said photosensitive layer photographic material, including a silver halide developer, for forming a transfer print of said latent image and wherein the absorption of the liquid from the layer of processing agent increases the concentration of the solid film-forming colloid between said sheet materials and produces between said sheet materials a coating of said colloid for receiving part at least of said transfer print, said colloid normally solidifying to form a solid film having a glossy surface, the improvement in said method which comprises the step of dispersing in the liquid processing agent, prior to the solidification of its colloid, a finely comminuted solid substance relatively insoluble and inert in the processing agent and having a low refractive index, said substance imparting a matte surface to the solid film formed from the colloid and increasing the resistance of said film to cracking.

v10. The method of claim 9 wherein the finely comminuted substance is dispersed in the processing agent prior to the spreading thereof.

11. The method of claim 10 wherein the photographic material for forming the transfer print includes a silver halide solvent as well as the silver halide developer.

12. The method of claim 11 wherein the silver halide developer and the silver halide solvent are contained in the liquid processing agent prior to the spreading thereof.

13. The method of claim 9 wherein the finely comminuted substance is silica aerogel.

14. The method of claim 9 wherein the finely comminuted substance is diatomaceous earth.

15. The method of claim 9 wherein the finely comminuted substance is wood flour.

EDWIN H. LAND.

REFERENCE S CIT ED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,277,048 De Brayer Aug. 27, 1918 2,196,226 Murray et ,al. Apr. 9, 1940 2,211,498 Files May 13, 1940 2,299,694 Green Oct. 20, 1942 2,315,966 Knott Apr. 6, 1943 2,317,750 Fermazin Apr. 27, 1943 2,317,789 Marriot Apr. 27, 1943 2,347,640 Peters May 2, 1944 2,352,014 Rott June 20, 1944 2,388,894 Yackel Nov. 13, 1945 2,417,924 Gary Mar. 25, 1947 2,543,181 Land Feb. 27, 1951 FOREIGN PATENTS Number Country Date 567,011 Germany July 22, 1931 879,995

France Mar. 5, 1942 

5. A PHOTOGRAPHIC PROCESSING COMPOSITION FOR FORMING TRANSFER PRINTS OF LATENT IMAGES CONTAINED IN SILVER HALIDE EMULSIONS, WHICH COMPOSITION COMPRISES A SILVER HALIDE DEVELOPER, A SOLVENT INCLUDING WATER FOR SAID DEVELOPER, AN ALKALI, A WATER-SOLUBLE SILVER HALIDE SOLVENT, A WATERSOLUBLE FILM-FORMING PLASTIC, SAID PLASTIC FORMING A SOLID FILM UPON REMOVAL OF THE LIQUID CONTENT OF SAID COMPOSITION, AND A WATER-INSOLUBLE FINELY COMMINUTED SOLID SUBSTANCE CHEMICALLY INERT TO THE DEVELOPER, ALKALI, SILVER HALIDE SOLVENT AND PLASTIC, SAID COMPOSITION, WHEN SPREAD IN A THIN LAYER BETWEEN A PHOTOSENSITIVE SILVER HALIDE EMULSION CONTAINING A LATENT IMAGE AND A PRINTRECEIVING LAYER, BEING CAPABLE OF FORMING A TRANSFER PRINT OF SAID LATENT IMAGE AND OF FORMING A SOLID FILM OF SAID PLASTIC THROUGHOUT THE SPREAD AREA WHEN THE LIQUID CONTENT OF THE COMPOSITION HAS BEEN ABSORBED AND EVAPORATED THEREFROM, SAID FINELY COMMINUTED SUBSTANCE IMPARTING A MATTER SURFACE TO SAID FILM AND INCREASING THE RESISTANCE THEREOF TO CRACKING. 